First built AR-15 won’t chamber next round

[Joeldiaz]

AR-15 won’t chamber next round

I recently built my first AR-15. It’s a BKF complete 14.5 upper with a Muzzle device pinned and welded on an Anderson lower I assembled myself from a lower parts kit. Has a standard carbine buffer and buffer spring. After firing it’ll eject the spent round but won’t load the next round in the magazine. It does indeed charge the gun because I can pull the trigger afterwards and it still clicks. In order to load the next round I have to eject the mag and reinsert it in order to manually charge the gun and allow the BCG to pick up the next cartridge. I was thinking I may need to switch out either the buffer or buffer spring from standard to some sort of combination of either heavier or lighter buffers or springs. Am I correct in this assessment? If not, what could be the issue? If so, what combo would I need to use? H1, H2, H3, Sprinco Blue, Yellow, Green, etc? Any help is greatly appreciated.

 

[1903Collector]

Love to help ya out but I haven't figured why my last build keeps f***ing up, good luck! Oh yea, probably gonna need to give more details on the build. Off the cuff it sounds like your short stroking.

 

[jakeroub]

Sounds like it isn’t cycling far enough to the rear. Does it function properly if you manually pull the charging handle?

Sufficiently lubricated?

How many round have you fired so far? Might just need to be broken in…

 

[greencobra]

tried a different mag?

 

[MAD Geary]

I’ve seen this happen before, first thing I would do is change the buffer spring. What brand spring / stock kit did you get?

 

[Joeldiaz]

Sounds like it isn’t cycling far enough to the rear. Does it function properly if you manually pull the charging handle?

Yeah it functions no problem if I manually charge it myself. I can pull the charging handle and load each round of a mag individually if I really wanted to.

Sufficiently lubricated?

I would hope so. I lubed it up so much it’s pretty much leaking lube from the creases where the upper meets the lower. Maybe it’s lubed too much?

How many round have you fired so far? Might just need to be broken in…

Not even a full mag. This was my first time testing it out.

 

[1903Collector]

I just re-read your post, why do you need to drop the mag and reinsert to manually load? are you getting doubles?

 

[Joeldiaz]

I’ve seen this happen before, first thing I would do is change the buffer spring. What brand spring / stock kit did you get?

BCM

 

[Joeldiaz]

tried a different mag?

Tried it with 2 different preban 30 rounders, same issue

 

[Joeldiaz]

I just re-read your post, why do you need to drop the mag and reinsert to manually load? are you getting doubles?

I guess you’re right, I don’t have to drop the mag. It was just something I did after each time to make sure the mag was fully seated.

 

[SIGNES]

You might be on to something with 'it works again when manually loaded after a reseat'. Mag partly unseating when fired due to the release being loose, sticky or slightly off position?

 

[50wt]

Remove the weights from the buffer and see what happens. Gas block lined up correctly? Gas key loose ?

 

[Mesatchornug]

Could be too little gas... which can be fixed by playing with the spring and buffer if the gas block isn't adjustable. If you have access to a borescope, you might make sure the gas port isn't blocked or misaligned.

 

[Joeldiaz]

Remove the weights from the buffer and see what happens. Gas block lined up correctly? Gas key loose ?

I’m honestly not sure, this was my first AR that I built but putting the upper together seemed intimidating so I bought a complete BKF one assuming it’d be good to go right out of the box. Can I still make adjustments to the gas block and key with the comp pinned and welded?

 

[Joeldiaz]

Could be too little gas... which can be fixed by playing with the spring and buffer if the gas block isn't adjustable. If you have access to a borescope, you might make sure the gas port isn't blocked or misaligned.

No borescope unfortunately. I’ll look into an adjustable buffer system and some different springs

 

[whatluck]

Did you clean and lube it? Does the BCG move freely? If so, the gun is probably undergassed. Probably an improperly installed gas block if I had to guess.

 

[Joeldiaz]

Did you clean and lube it? Does the BCG move freely? If so, the gun is probably undergassed. Probably an improperly installed gas block if I had to guess.

Yes, it’s has been cleaned and lubed and the BCG moves freely.

 

[Mountain]

Chasing down these things can be aggravating. If you had assembled the upper, I'd say first check the gas block position which is what I do if one of my builds isn't picking up the next round. BKF gets good reviews on arfcom, which can be a brutal site if a vendor has a few issues. Probably very unlikely that the gas block is misaligned but it's possible.

Given it's your first, I'll assume you don't have another known good lower. If possible to borrow for a moment, I'd try a different lower. If it now works, you have an issue with your lower. You can easily swap buffers and springs to see if that is the issue. If that's not the issue, it's easy to swap in a different BCG to check that. If the BCG is the issue, check the gas key.

Others have given some good advice on what to check, so nothing more for me to add.

 

[Tartakovsky]

You running full powered ammo? Is your gas block properly aligned? If both yes, you may want to open up your gas port a bit.

 

[BTSDOG]

Anti-tilt followers and new springs in magazine ?

 

[BTSDOG]

Im also assuming factory ammo ? If reloads, make sure overall length not too long for magazine...

 

[Joeldiaz]

Im also assuming factory ammo ? If reloads, make sure overall length not too long for magazine...

Factory Winchester 62 grain .223 ammo

 

[Joeldiaz]

Anti-tilt followers and new springs in magazine ?

Nope, just regular old preban 30 rounders. They worked fine in my Sig MCX.

 

[50wt]

Can you slide the gas block forward enough to measure the hole ? Take some photos if you can.

Removing the weights from the buffer should allow it to cycle if it is undergassed .

 

[Dench]

AR-15 won’t chamber next round

I recently built my first AR-15. It’s a BKF complete 14.5 upper with a Muzzle device pinned and welded on an Anderson lower I assembled myself from a lower parts kit. Has a standard carbine buffer and buffer spring. After firing it’ll eject the spent round but won’t load the next round in the magazine. It does indeed charge the gun because I can pull the trigger afterwards and it still clicks. In order to load the next round I have to eject the mag and reinsert it in order to manually charge the gun and allow the BCG to pick up the next cartridge. I was thinking I may need to switch out either the buffer or buffer spring from standard to some sort of combination of either heavier or lighter buffers or springs. Am I correct in this assessment? If not, what could be the issue? If so, what combo would I need to use? H1, H2, H3, Sprinco Blue, Yellow, Green, etc? Any help is greatly appreciated.

If you have another lower try it on the upper. In the tiny chance that the lower is the problem I'd take a peek at the mag release. I've seen cases where the mag release held the magazine at the incorrect height which would make the bolt stripping the round off the magazine all sorts of interesting.

 

[PappyM3]

No borescope unfortunately. I’ll look into an adjustable buffer system and some different springs

Don’t go out and get an adjustable buffer.

And before you mess with springs/buffer weights, make sure the gas block is properly aligned on the barrel.

Then, make sure the gas key on the carrier is solid, properly staked, and not loose.

If both of those seem good, I would personally remove the gas block and use a pin gauge to check the gas port size. They’re not that expensive on Amazon, but you might be able to borrow some from someone. If you do get a pin gauge set, check the gas key inner diameter too.

You’re running a carbine spring and buffer. A failure to feed is very likely caused by too little gas. Rather than too little spring/buffer.

If you have another lower try it on the upper. In the tiny chance that the lower is the problem I'd take a peek at the mag release. I've seen cases where the mag release held the magazine at the incorrect height which would make the bolt stripping the round off the magazine all sorts of interesting.

Yeah, it would be helpful to isolate the issue. I’d probably try someone else’s upper on his lower first. Gas systems on cheap uppers are the cause of issues much more often than out of spec lowers. BUT, it still could be a mag position issue like you mention. Definitely worth looking at if the problem persists.

 

[cams]

3 weeks later listed in NES classifieds as custom build for $2K.

 

[22lr]

As others have said, I doubt the issue would be the buffer / spring. If I were you, I would first try a mag with a new spring and an anti tilt follower just to be safe. And if you are still having issues, I would reach out to BKF and see what they say. There may be a known issue on your batch or maybe they will check it out for you.

 

[sschevy]

The action is Short stroking , measure the gas port and then open it up

Because it’s too small , like every other budget complete upper on the market

 

[PappyM3]

…
Because it’s too small , like every other budget complete upper on the market

Except for the ones that are severely over-gassed